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Chapter 5

Chapter 5 - Variations in Consciousness.docx

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PSYC 1010
Jennifer Steeves

Chapter 5 – Variations in Consciousness The Nature of Consciousness • Consciousness involves varied levels of awareness • Mental processes continue during sleep; some stimuli can penetrate awareness • Research suggests that decisions made when people do not have the chance to make conscious deliberations may sometimes be more accurate • The evolutionary significance of consciousness is a matter of debate • Changes in consciousness are correlated with changed in brain activity as measures by EEGs Biological Rhythms – Relation to Sleep • Circadian (~24-hour) Rhythms are influential in the regulation of sleep and temperature • Infradian (< Once/day, < 1 year) Rhythms are influential in menstruation and egg- laying in fish  Circannual (~1 year) Rhythms are influential in regulating migration and hibernation • Ultradian (<1/day) Rhythms – influential in regulating heartbeat, respiration, cycles w/i sleep • Internal biological clocks are reset by exposure to light  stimulates SCN  signals pineal gland to secrete melatonin • Poor sleep associated with jet lag and rotating shift work is due to being out of sync with CRs  Administration of melatonin and exposure to bright light appear MAY help realign them Sleep The Architecture of Sleep • Electroencephalogram (EEG) – Measures voltage diff. between any 2 points on the scalp  Different states  Different Waveforms  Specific wave forms are reliably associated with specific states  Irregular High-Frequency Noise – Each neuron is doing its own thing  Regular Low-Frequency Noise – Neurons are doing things in synchrony • Different waves characterize different stages  Alpha Waves – Awake but non-attentive; unsynchronized activity  Beta Waves – Awake and attentive; unsynchronized activity  Delta Waves – Sleep Stages  REM Sleep – irregular high frequency waves indicate unsynchronized activity  Middle Stages – weird blips; sleep spindles  Deep Sleep – Low frequency waves indicate synchronized activity; E.g. Stage 4 • Non-REM Sleep – consists of stages 1-4 that are marked by:  Absence of rapid eye movements  Relatively little dreaming  Varied EEG Activity • REM Sleep – deep stage of sleep marked by:  Rapid eye movements  High-frequency  Brain waves  Dreaming • Usually progression from Stage 1-4 and then back up and into REM sleep • First REM period after ~90 min. (if not sleep-deprived) and in ~90 min intervals after that • During sleep REM periods gradually get longer and non-REM periods get shorter and shallower • Spend more time in deep stages in early evening, more time in light stages towards morning • The architecture of sleep varies somewhat from one person to the next Why Do We Sleep? • No one knows for sure, but there are theories 1. Restoration Theory  Your body needs to rest and recover  Runners sleep more after a marathon  Regular exercise can help sleep 2. Preservation Theory  Why risk being killed if you can only get food in the day? Brain Structures Involved in Sleep • Reticular Activating System (RAS)  Stimulation  awake-like EEG waves  Damage  coma, sleep-like EEG waves • Pons (bridge)  Damage to pons can reduce or abolish REM sleep  Has connections to other brain areas to activate cortex, start eye movements, and block movements during REM Factors Influencing Sleep • REM Portion of Sleep – declines from 50% among newborns to about 20% among adults • Time in slow-wave sleep declines during adulthood • Culture does not appear to have much effect on the architecture of sleep • Culture does influence napping practices and co-sleeping; normative in many societies • Many brain structures and neurotransmitters contribute to the regulation of sleep Sleep Deprivation • Become really tired; especially 2:00 – 6:00 am • Can cause lapses in attention and memory • Microsleeps – Fall asleep for a few seconds or a minute; become less responsive to stimuli  People are unaware they blanked out; Driving tired can be worse than driving drunk • Partial Deprivation (common) – Can impair alertness and appears to contribute to accidents • Selective Deprivation (REM and slow-wave sleep) – Leads to increased attempts to shift into these stages of sleep and increased time spent in these stages after sleep deprivation • Memory Consolidation – REM and slow-wave sleep help firm up learning from during the day • Short sleep duration is associated with a variety of health problems • Both short & long sleepers exhibit elevated mortality rates Insomnia • Fairly common sleep disorder with many diverse causes  E.g. possibility that insomniacs have a higher arousal level • Occurs in 3 Patterns:  Difficulty falling asleep  Difficulty remaining asleep  Persistent early morning awakenings • Sedative drugs are a poor long-term solution because:  Risk of overdose  Escalating dependency  Carryover drowsiness Other Sleep Problems • Narcolepsy – Marked by sudden and irresistible onsets of sleep during normal waking periods • Sleep Apnea – Involves frequent, reflexive gasping for air that disrupts sleep • Nightmares – Anxiety-arousing dreams tha
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